A variety of glue guns have been disclosed, and have appeared on the market. These glue guns include electric glue guns, which use positive-coefficient-temperature electric heaters to produce heat for melting glue sticks, and gas-burning glue guns, which burn fuel gas to melt glue sticks. The common drawback of electric glue guns is that electric glue guns can only be operated within the reachable distance of electric cables. The major advantage of gas-burning glue guns is the mobility. However, when a gas-burning glue gun is used, the gas control switch must be frequently switched on and off during the operation. Furthermore, these gas-burning glue guns are not durable in use because they commonly use heat conductive pads fitted into the combustion chamber to transmit heat to the glue stick.